Changes in body mass index in a Finnish population between 1972 and 1982.

Population-based data on changes in body mass index are scarce. We have examined about 9700 people aged 30-59 years in two provinces of East Finland in 1972, 1977 and 1982. The age adjusted mean value of body mass index (kg m-2) in 1972 was 26.0 +/- 3.4 in men and 26.9 +/- 4.7 in women, increasing with age. During the 10-year follow-up the mean body mass index increased in men to 26.5 +/- 3.6 (P less than 0.001). In women we found a decrease in mean body mass index to 26.4 +/- 4.9 (P less than 0.001). The increase trend in body mass with age remained in women, while in men the age trend increased from survey to survey. The proportion of obese men also increased while in younger women a decrease was observed. The results of this study show the association between changes in physical activity, education etc. and the observed changes in the body mass index.